#100DaysOfCode in Python Transcripts
Chapter: Days 31-33: Logging
Lecture: Demo: File logging
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So far, we've got this almost unreadable log goo
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mixed in with our standard user input/output.
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So it's really,
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it's nice that we can see what's going on,
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but it's really not helpful for us here.
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So let's change this.
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Let's just go down here and, to our program,
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and when we init the logging, instead of passing in nothing,
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we're going to pass in a file name,
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and that's going to go to the timed rotating file handler,
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the same level rather than the standard out.
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Okay, so let's go down here, and let's,
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we'll just call this movie app.log, something like this,
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and run it again.
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Alright, now it's back to the way it was before
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in terms of interactions.
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There's none of that mess around.
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Let's search for action again.
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And it runs, and we get our nice output, and, ta-da!
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Let's run it one more time.
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Let's search for hero.
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Ah, we got a bunch of good stuff with heroes and so on.
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And let's run it with an error.
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Nope, must search for something.
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Alright, how about jazz.
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Anything there? Hmm, looks like there is.
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Pretty cool, so that's great.
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Our app is working again, but notice,
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notice over here, we now have a movie-app.
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Instead of .log, it has 2018-02-23,
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because that's today, that's when I'm recording this
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right now, so let's look and see what's in there.
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So you can see it's exactly the same messages.
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Here's the app is starting up.
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Here's the app starting up again.
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Things like that, here's another startup.
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And these are all the messages.
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We started a search for action, we got a 200.
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We got eight results, that long.
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Alright, and you can see the time of day
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to the super accurate right there.
1:44
Again, we're starting up, and this time we searched
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for hero and got 10 results.
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This time we searched for nothing,
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and we got a warning, and so on.
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Okay, so we have this log file here,
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and it's not super important,
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it's less important, let's say, when you're writing
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a regular app, 'cause you could just put
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the data and time in the log file.
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But if you're writing a super long running service,
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like a web application that starts and runs
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basically indefinitely, or
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some kind of queuing application that's just listening
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for messages and is going to run,
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basically anything on the server
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that starts and just runs,
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the ability to have it automatically rotate -
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when it becomes the 24th, the next log message
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will just start a new file, for example.
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So really really nice to have this timed,
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rotating file handler here.
